1. Field of the Invention
The present invention relates to a copying machine and, more specifically, to a copying machine capable of copying images on both sides of a single copying paper, respectively, on a reduced scale to provide appropriate filing margins on both sides of the copying paper, respectively.
2. Description of the Prior Art
A copying machine capable of copying images on both sides of a single copying paper has been proposed. This proposed copying machine comprises a duplex unit which inverts a copying paper having an image on one side and refeeds the inverted copying paper to the image forming unit.
There has also been proposed a copying machine capable of shifting an reduced image on a copying paper in the direction of conveyance of the copying paper to provide a filing margin on the copying paper.
In case of copying first and second single-sided documents or a double-sided document which have no filing margin on both sides of a single copying paper, respectively, by the conventional copying machine, the filing margin on the first side of the copying paper and the filing margin on the second side of the copying paper are formed on the opposite edges of the copying paper, respectively. Such filing margins cannot be used in filing the paper.
Such a failure in properly forming filing margins on both sides of a copying paper results because the copying paper is inverted by a duplex unit after the image of a document has been copied on the first side of the copying paper, and then the inverted copying paper is fed again to the image forming unit, so that a filing margin on the second side is formed on an edge opposite to the edge where a filing margin on the first side is formed.
For example, as shown in FIG. 2, when the image A of a first document is copied on the first side of a copying paper on a reduced scale, a filing margin a is formed adjacent to the trailing edge of the copying paper. This copying paper carrying the image copied on the first side is inverted so that the copying paper is turned upside down and the leading edge and trailing edge thereof are reversed, and then the inverted copying paper is stored in a temporary storage tray. Then, the inverted copying paper is fed in a direction indicated by an arrow E with the edge having the filing margin a running a head. Then, the image B of a second document is copied on the second side of the copying paper. Accordingly, the filing margins a and b are formed adjacent to the opposite edges of the copying paper, respectively.